A method is known for producing an electrochromic device (U.S. Pat. No. 4,902,108, 20 Feb. 1990), wherein a thickened solution of polymethyl methacrylate in a low-boiling solvent is applied onto a conducting layer of one of two optically transparent electrodes, then the solvent is evaporated to give a polymethyl methacrylate layer. Thereafter the optically transparent electrodes are glued together along the perimeter at a specified distance from each other and a closed space between them is filled, through a hole (holes) in the glue line, by an electrochromic solution comprising cathodic and anodic components and an inert electrolyte in a high-boiling solvent, and the said space is sealed. The said polymethyl methacrylate layer dissolves and thickens the electrochromic solution, that results in decreasing appreciably the adverse effect of the gravitation-induced “stratification” of the electrocoloured form of the composition. Thus, the proper electrochromic composition is prepared only after completion of the assembling the said electrochromic device, that restricts the workability of the device as a whole. The electrochromic composition is a liquid phase with a variable viscosity, determined by the amount of the thickening polymer. The inert electrolyte added to the electrochromic solution ensures the electrical conduction of the latter in the case where the cathodic and anodic components are not ionized on dissolution.
A method is known for producing of an electrochromic device (U.S. Pat. No. 5,471,337, 28 Nov. 1995), wherein closed space between electrodes is filled with an electrochromic disperse system, consisting of a dispersion medium, in the form of a solvent thickened preferably with polymethyl methacrylate or a solvent-plasticized polymer, and a disperse phase, comprising a cathodic component such as polyoxometallate and an anodic component. Since polyoxometallate is an inorganic electrochromic component and, therefore, it has a lower extinction coefficient than organic electrochromic components, thus prepared electrochromic device does not ensure a sufficient efficiency of light attenuation without a substantial energy consumption.
A method is known for producing an electrochromic device (RU 2144937 C1, 27 Jan. 2000), wherein closed space between the electrodes is filled with an electrochromic disperse system, the said system is a suspension and consists of a dispersion medium in the form of an electrochromic solution, comprising cathodic and anodic components, and a solvent, as well as a disperse phase in the form of a finely dispersed polymer; the space is sealed and the electrochromic disperse system is kept until the polymer dissolves. This method allows producing rather easily an electrochromic device with a broad range of viscosities of the electrochromic composition up to a solid-like film, which prevents “stratification” of the electrocoloured forms of the components of the said composition and reduces the risk of contact with the electrochromic composition on accidental destruction of such device. However, on long-term exposure to a voltage and, especially on changing the polarization polarity after such an exposure, as well as on the application of high voltages (more than 2 V), “spots”, i.e., areas that differ in the colour and/or colour intensity from the background, appear in the electrochromic composition of the known electrochromic device (RU 2144937 C1, 27 Jan. 2000). This adverse effect is mainly typical for electrochromic devices having a large work surface area of optically transparent SnO2:F-electrodes. Besides, in the process of producing the electrochromic device, after dissolution of the polymer and clarification of the electrochromic composition, air bubbles appear over the whole work surface of the device, which makes the device unserviceable.
Methods are known for producing an electrochromic device, the methods including steps of producing a solid-like film of the electrochromic composition directly in the device by polymerization and/or cross-linking polymerization of the chains in monomer compositions by means of various initiators (EP 0612826 A1, 31 Aug. 1994; WO 97/34186, 18 Sep. 1997; WO 98/42796, 1 Oct. 1998). However, polymerization reactions are accompanied by volume shrinkage, which has an adverse effect on the quality of the electrochromic device. The adverse effect can become apparent especially in electrochromic devices with relatively large inter-electrode gaps (1-2 mm), which are usually provided in electrochromic devices with large work surfaces (more than 0.5 m2).